1. Field of the Invention
The invention relates to footwear, and more particularly to an article of footwear, such as a shoe, intended for the practice of a sport.
Footwear of the invention encompasses that which can be used in disciplines such as walking, including power walking, running on either flat or mountainous terrain, climbing, skateboarding, a ball sport, or the like.
2. Background Information
Footwear, such as a shoe, can include a low upper, a mid-upper, or a high upper, i.e., an upper having an uppermost edge positioned, respectively, below the ankle, at or near the middle of the ankle, or above the ankle. The shoe can also be relatively flexible or more rigid. However, regardless of its general appearance or the sporting activity performed, the shoe should meet the expectations of the user.
In particular, it is desirable that the shoe minimize user fatigue, which requires a shoe structure having a reduced mass. This characteristic is important in all disciplines mentioned above, especially running and walking. Indeed, a reduced mass translates into low inertia and, therefore, less fatigue.
To reduce the mass of a shoe, it is known to provide through-openings in the wear layer, i.e., the outsole. The wear layer, which is provided to be supported on the ground, is generally comprised of rubber, a material having high adherence capability, but also high density. For this reason, openings can be provided to lighten the wear layer, and therefore the entire shoe.
In the fields of running or walking, for example, it is known to cut transverse slits in the wear layer. These slits lighten the shoe and also promote longitudinal bending of the outer sole assembly for facilitating a good foot rolling movement.
However, the openings in the wear layer occasionally give rise to punctures. Indeed, each opening constitutes an interruption of the wear layer, thereby forming a passageway for any foreign object that could become lodged therein. Such foreign objects may be pieces of minerals, branches, any of various ground projections, or small objects such as pebbles, debris, and the like. The introduction of a foreign object into an opening can cause deformation or deterioration of the outer sole assembly, and possibly injuries to the foot of the user.
To overcome the problem related to punctures, it is known to seal the bottom of an opening, at least partially, with a reinforcing layer arranged between the wear layer and the remainder of the sole assembly of the shoe. The reinforcing layer is generally comprised of a thin synthetic material. This provides the reinforcing layer with both puncture resistance and reduced mass, thus enabling the sole assembly to remain light.
Finally, a shoe made with openings in its wear layer is both lighter and more resistant to punctures. However, such a shoe has the disadvantage of having reduced ground-gripping ability. This means, for example, that the shoe can slip when subject to a force that would be insufficient to cause a shoe of equal size, but with no openings, to slip. This type of slip, or ill-timed sliding, can occur when applying a supporting force toward the ground, especially on an inclined surface, and when forces related to acceleration, braking, or the like, are exerted. As a result, walking or running is less precise, less safe and, paradoxically, causes user fatigue.